The starting point for the invention is a device for atomising liquid metals as generically categorised in the preamble of claim 1 and a process as generically categorised in the preamble of claim 2.
The atomisation of metals for the purpose of producing a powder for powder-metallurgical and other applications has been publicised for a long time and is known from an extensive technical literature. Of the possible processes, the atomisation process using a gas jet (air, nitrogen or noble gas) is favoured. A known device for gas jet atomisation possesses, as an essential component, a centrally symmetrical body for guiding the liquid metal to be atomised (metal jet) and the atomising gaseous medium (gas jet), a so-called nozzle (cf. for example U.S. Pat. No. 2,997,245). A device of this type is intended to spread the liquid metal jet as completely as possible into individual small droplets.
In powder metallurgy, then, there are applications where it would appear to be desirable to increase to extremely high values the rate of cooling during the solidification of the droplets, in order to realise very specific, controlled structures. In particular, the intention is in this way to avoid segregations out of saturated or supersaturated melts and to obtain homogeneous structures. That in turn necessitates a special device which enables very well defined gas-dynamic conditions to be realised in the atomisation zone. The existing devices and nozzles satisfy these conditions only inadequately, if at all.
There is therefore a great need to improve existing metal atomisation devices and methods in such a way that the abovementioned effects can be removed as far as possible.